Objective The objective of this study was to present epidemiologic data on infantile hypertrophic pyloric stenosis (IHPS) from seven well-defined European regions and compare incidence and changes in incidence over time between these regions.

Methods The study is a population based study using data from registries of congenital malformations (EUROCAT) for more than two decades (1980–2002).

Results A total of 2534 infants were diagnosed with IHPS during the study period giving an overall incidence of IHPS at 2.0 per 1000 livebirths (LB) ranging from 0.86 per 1000 LB to 3.96 per 1000 LB in the seven regions. A significant decrease in incidence was observed in two regions and a significant increase in incidence was observed in two other regions.

The large majority of infants were boys (82%). Mean birthweight was 3310 g and median gestational age at birth was 39 weeks with 11% born before 37 weeks. Diagnosis of IHPS was made before 4 weeks of age for 38% and after 4 weeks for 60%

Conclusions There were significant differences in the incidence of IHPS in the seven European populations. No uniform pattern of change in incidence was observed as the populations also differed in relation to trend over time with both significant increases and decreases over time. The data cannot support the theory that sleeping position has an impact on the incidence of IHPS.